1. Field of the Invention
This invention generally relates to marking and retraction needles of the type used to mark the location of tumors prior to surgery or to secure a prostate during surgery, respectively, and specifically relates to a marking and retraction needle having a retrievable stylet.
2. Description of the Prior Art
Small tumors in the breast are often removed by surgical procedures; obviously, the surgeon must be able to easily locate the tumor or area to be removed if unnecessary tissue removal is to be avoided.
The art has developed a device known as a marking needle or localizer that marks the location of the tumor to be removed. Preparatory to surgery, the tip of the needle is placed adjacent the tumor to be removed, and an anchoring means is employed to prevent the needle tip from extracting itself from its position adjacent the tumor.
The anchoring means now in widespread use is a stylet in the form of an elongate thin wire with a barb formed in its distal end, which stylet is received within a hollow needle.
When the needle is satisfactorily positioned, the stylet is axially advanced, i.e., it is pushed forwardly out of the needle. It is then retracted a very short distance so that the barb can engage and hook tissue. The needle is then removed, leaving the stylet behind. Since the proximal end of the stylet extends out of the patient's body, it remains visible and serves as the marker that guides the surgeon to the tumor.
There are a number of problems with the marking needle just described, even though it is in widespread use as aforesaid.
Once the stylet is in place, X-rays are taken to determine whether or not the stylet is in its optimal position. Typically, the breast will be compressed in two directions, i.e., it will be subjected to oppositely directed vertical forces and oppositely directed lateral forces. In other words, it is squeezed either up and down or left to right, or both, and X-rays are taken.
Unfortunately, the squeezing tends to drive the stylet in deeper because the compression urges the barb to burrow, i.e., to work itself in a forward direction.
If the stylet were not provided with a hook, however, the squeezing would cause the needle to work its way out of the patient's body.
Once the X-rays have been taken, it may be determined that the hooked stylet is not ideally positioned and that, accordingly, its position should be changed. However, relocation necessarily requires retraction of the stylet from the patient's body. The barb or hook prevents such retraction. In fact, the only way to remove the stylet is by surgery; this is ironic since the primary purpose of the stylet is to avoid unnecessary tissue removal.
The stylet left in the body to mark a tumor location may itself be cut inadvertently during the surgical attempt to remove the tumor. The stylet is a small gauge wire having a diameter of about a ten-thousandths of an inch (0.0010"). It is not easily seen and therefore is likely to be severed. In fact, it is severed frequently by the surgeon's scalpel. Obviously, since the stylet must be surgically removed as aforesaid, a severed stylet increases the difficulties faced by the surgeon.
The severing of the stylet may be avoided by slipping a protective tube over it, but this is not an entirely satisfactory solution to the problem since it necessitates use of the protective tube.
The benefit of being able to pinpoint a tumor prior to surgery outweighs the detriments associated with use of the conventional marking needle, however, and the art has simply accepted its shortcomings.
Marking needles are also used to to help anchor prostate glands against movement as required in certain surgical procedures. Many of the above-mentioned shortcomings also apply when the needles are used in prostate surgery. When used to anchor a gland against movement, the needles are known as retraction needles.